Cystocentesis
Cystocentesis is used to obtain sterile samples of urine from the bladder.
Summary of the Procedure:
| Indications | Obtaining a urine sample for urinalysis, relieving distension due to urethral obstruction. |
| Limitations | May introduce blood into urine sample. |
| Complications | Urinary tract hemorrhage, urine leakage into peritoneal cavity (usually insignificant), ruptured bladder (rare). |
| Contraindications | Marked bleeding disorder, pyometra, urinary bladder cancer (transitional cell carcinoma – cystocentesis could spread tumour cells along needle tract). |
| Supplies/instruments | 12 mL syringe
22-23 ga needles, length of 1 to 1.5 inch (1.5 inch usually in larger patients) Isopropyl alcohol |
| Position | Most commonly dorsal recumbency
Can also use lateral recumbency or perform standing. |
| Restraint | Manual, sedation, anesthesia. |
Landmarks:
Male dog:
- Palpate bladder with one hand and immobilize.
- If the bladder is not palpable, the following blind technique may be used: Penetrate the needle into the abdomen just lateral to the prepuce, approximately halfway between the tip of the prepuce and the scrotum when in dorsal recumbency.
Female dog:
- Palpate bladder with one hand and immobilize.
- If bladder is not palpable, then two blind techniques may be used with the female dog in dorsal recumbency:
- 1) Pour alcohol onto the caudal abdomen, observe where it pools, and direct the needle straight downwards;
- 2) Palpable the cranial rim of the pubic bone, and direct the needle straight downwards slightly cranial to the rim.
Cats:
- Palpate bladder with one hand and immobilize.
Details of the Procedure:
- Swab the puncture site with alcohol; alternatively use a surgical prep. Local anesthesia is usually not used, but if desired EMLA cream may be used (usually not performed in most cases).
- Attach needle to syringe, break the seal on the syringe by aspirating a bit of air and then emptying the syringe.
- Palpate the bladder with non-dominant hand and stabilize the bladder.
- Needle is placed perpendicular to abdominal surface; some will recommend a slight angle toward the pelvis when placing the needle and this will be helpful if the bladder is small.
- Aspirate gently on the syringe to obtain urine.
- Stop aspirating (i.e. release negative pressure) prior to withdrawing the needle.
- Remove needle and replace with new sterile needle to transfer contents to urine culture vial (or expel sample from syringe directly without a needle)
Variations:
- Ultrasound can be used to verify bladder location when bladder is small and difficult to palpate, or if there is concern about other intra-abdominal disease such as a mass in the same region.
- However, note that blind cystocentesis when bladder is palpable or using the above landmarks is an accepted procedure, and ultrasound is not a requirement.
Video of Cystocentesis in a Cat:
(Two notes on the video: 1 – the clinician here is using a sterile prep and surgical gloves, not all clinicians will use this level of asepsis for the cystocentesis; 2 – the first 2 minutes is the prep, so you can skip to the 2:05 mark to get to the actual cystocentesis)
Video of Cystocentesis in a Dog:
(Two notes on the video: 1 – the first 40 seconds is the prep, so you can skip to the 0:40 mark to get to the actual cystocentesis; 2 – no needle caps in your mouth!)